The present invention is directed to a process and device for producing a reaction mixture forming solid material or foamed material from liquid flowable reaction components, wherein at least one of the flowable reaction components comprises filling material. According to the invention, the reaction components are transported from at least one storage container by pumps and metered under high pressure into a mixing head.
Reaction components charged with filling material, such as those used in the manufacture of polyurethane articles, are known to possess high abrasive properties. As a result (and for economic reasons), the processing of such filled reaction components are prohibited in conjunction with particular devices, e.g. high pressure injection mixheads, requiring injection of the components (polyol and isocyanate) into the mixing chamber of the mixhead at pressure of above 100 bar and up to 300 bar.
Reaction components without filling material can be delivered using conventional high-speed, high-pressure piston pumps, subjected to high pressure such as 120 to 250 bar, metered, and then injected into the mixing chamber of a high-pressure mixing head. However, delivery of reaction components with filling material through such piston pumps is not possible. Normally, gear pumps may be used up to a pressure of about 100 bar at 1.500 to 3.000 rpm.
In producing certain articles, the high-pressure intermixing of reaction components charged with filling materials is indispensable. Even though wear by virtue of the abrasive filling materials can never be entirely eliminated, slow-running piston-type metering instruments or plunger pumps have been employed with success. However, such instruments have the disadvantage of a large overall height, with all the related disadvantages of maintenance. Additionally, the structure of such instruments is very elaborate and, therefore, expensive.
For the foregoing reasons, it would be desirable to develop a process and device for pressurizing to high pressure, reaction components charged with filling material by using instruments which are simply constructed and moderately priced and which operate reliably and with less wear. This is achieved by the present invention in that the flowable reaction components charged with filling material are brought to the desired high pressure in several pressure stages with gear pumps having the same rotary speed which are connected in series and via pipelines.
It is an object of the present invention to provide a process for transporting flowable reaction components of a reaction mixture, at least one of the flowable reaction components comprising filling material, by bringing the flowable reaction components to a predetermined pressure in several pressure stages through the use of gear pumps operated at low rotational speed.
It is another object of the present invention to provide a device for transporting flowable reaction components of a reaction mixture, at least one of the flowable reaction components comprising filling material, the device comprising gear pumps connected in series via pipelines, wherein pressure is provided in stages to the flowable reaction.